Method for manufacturing smeiconductor device

Abstract

In one embodiment, a first insulating film is formed with a recess portion left therein in a contact hole, and the contact hole is surrounded by a first line pattern and a second line pattern, the first line pattern and the second line pattern having different heights. The recess portion is filled so as to form a first mask film, and the first insulating film except for the recess portion is etched back so as to be removed, thereby forming a second contact hole. After that, a conductive material is implanted in the second contact hole, and the top surface of the first line pattern having a low height is exposed, thereby forming a contact plug.

1 . A method for manufacturing a semiconductor device, comprising:
 forming a plurality of first line patterns extending in a first direction and arranged at predetermined intervals on a substrate;   forming a plurality of second line patterns which are at a higher level than the first line patterns and extend over the first line patterns in a second direction orthogonal to the first direction on the substrate;   forming a first insulating film having different etching selectivity than the surfaces of the first and second line patterns to a thickness that forms a recess between the second line patterns;   forming a first mask film which fills the recess and has different etching selectivity than the first insulating film on the first insulating film;   etching the first mask film to expose the first insulating film, the first insulating film is preferentially further etched so that the first insulating film below the first mask film in the recess remains, and an opening is formed which exposes part of the substrate surface enclosed by the first and second line patterns along the side surfaces of the second line patterns;   forming a conductive material by filling the opening; and   etching the conductive material back to expose the upper surface of the first line patterns, and forming a plurality of contact plugs which are separated in the second direction by the first line patterns and are separated in the first direction by the second line patterns and the first insulating film.   
     
     
         2 . The method for manufacturing a semiconductor device as claimed in  claim 1 , wherein the second line patterns have an inclined side surface shape forming, in the first direction, a predetermined bottom surface gap and an upper surface gap which is wider than the bottom surface gap. 
     
     
         3 . The method for manufacturing a semiconductor device as claimed in  claim 1 , wherein the forming the plurality of contact plugs is implemented by etching back the whole surface until the upper surface of the first line patterns is exposed. 
     
     
         4 . The method for manufacturing a semiconductor device as claimed in  claim 1 , wherein forming the plurality of contact plugs is implemented by etching back the whole surface to a predetermined height level, then etching back the conductive material until the first line patterns are exposed and a level at or below the upper surface of the first line patterns is reached. 
     
     
         5 . The method for manufacturing a semiconductor device as claimed in  claim 1 , comprising, after the second line patterns have been formed and before the first insulating film is formed, covering the substrate surface and the surfaces of the first and second line patterns by an insulating material having different etching selectivity than the first insulating film. 
     
     
         6 . The method for manufacturing a semiconductor device as claimed in  claim 1 , wherein the first line patterns are disposed at intervals which are no greater than twice the thickness of the first insulating film, the first insulating film is formed filling the areas between the first line patterns, and the recess has a substantially flat bottom surface. 
     
     
         7 . The method for manufacturing a semiconductor device as claimed in  claim 1 , wherein the first line patterns are disposed at intervals which are more than twice as wide as the thickness of the first insulating film, and the recess has a second bottom surface over the first line patterns and a first bottom surface at a lower level than the second bottom surface between the first line patterns. 
     
     
         8 . The method for manufacturing a semiconductor device as claimed in  claim 7 , wherein the first mask film includes a shape formed by the second bottom surface and the first bottom surface, a second insulating film having different etching selectivity than the first insulating film. 
     
     
         9 . The method for manufacturing a semiconductor device as claimed in  claim 1 , wherein the first insulating film is a silicon dioxide film and the first mask film is a silicon nitride film. 
     
     
         10 . The method for manufacturing a semiconductor device as claimed in  claim 1 , comprising:
 forming a plurality of element isolation regions extending in a third direction different than the first and second directions on the semiconductor substrate, and defining an active region extending in the third direction between the element isolation regions;   forming two pairs of adjacent embedded word lines extending in the second direction and forming an embedded dummy word line between the pairs of embedded word lines;   forming bit lines which are connected to the active region between the pairs of embedded word lines and are covered by an insulating film on the upper part and side surfaces on the semiconductor substrate as first line patterns; and   forming the second line patterns, the second line patterns extending in the second direction on the pairs of embedded word lines and opening over the active region on the embedded dummy word line and on both sides thereof,   wherein the contact plugs are connected to the active region on both sides of the embedded dummy word line.   
     
     
         11 . The method for manufacturing a semiconductor device as claimed in  claim 10 , comprising:
 after an insulating film has been formed on the lateral walls of the bit lines, performing etch-back until the semiconductor substrate surface in the region where the bit lines are not formed is exposed;   covering the whole surface with a liner insulating film having different etching selectivity than the first insulating film;   forming an embedded insulating film on the liner insulating film and filling the gaps between the bit lines;   forming a mask film on the bit lines and on the embedded insulating film, and forming the second line patterns including the embedded insulating film; and   forming a side wall insulating film having different etching selectivity than the first insulating film over the whole surface including the second line patterns, wherein the side wall insulating film and liner insulating film which are exposed at the bottom of an opening formed by preferentially removing the first insulating film are removed in order to expose the active region on both sides of the dummy word line.   
     
     
         12 . The method for manufacturing a semiconductor device as claimed in  claim 11 , wherein the first insulating film is a silicon dioxide film and the liner insulating film and side wall insulating film are silicon nitride films. 
     
     
         13 . The method for manufacturing a semiconductor device as claimed in  claim 10 , comprising forming a capacitor on the contact plug. 
     
     
         14 . The method for manufacturing a semiconductor device as claimed in  claim 13 , wherein the capacitor comprises a cylindrical lower electrode which is electrically connected to the contact plug and has a bottom surface and side surfaces, and an upper electrode which faces an inner wall and an outer wall of the lower electrode with a capacitance insulating film interposed. 
     
     
         15 . The method for manufacturing a semiconductor device as claimed in  claim 13 , comprising forming a pad electrode which electrically connects the contact plug and the lower electrode of the capacitor. 
     
     
         16 . A method for manufacturing a semiconductor device, comprising:
 forming a trench having a first bottom surface in an interlayer film, and forming a first contact hole having a second bottom surface at a lower level than the first bottom surface inside the trench;   forming a first insulating film to a thickness that forms a recess in the center between both lateral walls of the trench;   forming a first mask film filling the recess;   removing the first insulating film other than the first insulating film below the first mask film inside the recess to expose the first bottom surface and part of the second bottom surface; and   embedding a conductive material in contact with the first bottom surface and the second bottom surface.   
     
     
         17 . The method for manufacturing a semiconductor device as claimed in  claim 16 , wherein the first contact hole is formed into a shape in which a recess formed in the first insulating film is positioned in the center of the first contact hole in the trench width direction, the shape projecting further toward both lateral walls of the trench than the side surfaces of the recess in the trench width direction, and two second contact holes are formed by means of the remaining first insulating film by splitting the first contact hole. 
     
     
         18 . The method for manufacturing a semiconductor device as claimed in  claim 16 , wherein the first contact hole is formed into a shape that is provided further towards one lateral wall in the trench width direction, a recess formed by means of the first insulating film is positioned on one side end of the first contact hole, the shape projecting further toward one lateral wall of the trench than the side surface of the recess on one side surface of the trench, and two contact holes which are smaller than the first contact hole are formed by means of the remaining first insulating film. 
     
     
         19 . The method for manufacturing a semiconductor device as claimed in  claim 16 , wherein the conductive material is embedded, after which the conductive material on the first bottom surface is removed. 
     
     
         20 . The method for manufacturing a semiconductor device as claimed in  claim 16 , wherein the second bottom surface includes at least a conductive site having an underlayer structure at the region of contact with the conductive material. 
     
     
         21 . The method for manufacturing a semiconductor device as claimed in  claim 16 , wherein the interlayer insulating film and the first insulating film comprise an insulating material containing silicon dioxide, and the method comprises, before the first insulating film is formed, forming a second insulating film having different etching selectivity than the first insulating film in the trench including the first and second bottom surfaces and on the inner wall of the first contact hole. 
     
     
         22 . The method for manufacturing a semiconductor device as claimed in  claim 21 , wherein the first mask film and the second insulating film comprise silicon nitride.